According to the present invention an interlocking arrangement is provided for connecting the two end pieces of a paperboard carton blank having at least one flap projecting from a first one of the end pieces for cooperation with at least one respective opening defined in a end second end piece, of the paperboard carton blank the flap or flaps each having a leading portion spaced farthest from the remainder of the first end piece of the carton blank, behind which leading portion is a portion which projects laterally at least in one direction, the flap or flaps each being folded such that the leading portion and the laterally projecting portion are folded back on the rest of the flap, the flap is then inserted into its associated opening within the folded area or areas of the second piece first, so that when the laterally projecting portion of the flap passes through the opening it takes up a position clear of the edge of the opening, thereby preventing withdrawal of the flap while the leading portion thereof remains held by the opening. Such an interlocking arrangement can lie generally flat relative to the pieces of paperboard.
Preferably each flap has portions projecting laterally in both directions, the flap having a waisted section immediately behind the projecting portions, at which waist the flap is folded back along a straight line.
In preferred embodiments the opening comprises a single cut having two ends.
With chosen arrangements the laterally projecting portions are angled into the waist and into the leading portion. Also the maximum width across the laterally projecting portions of each flap is substantially the same as the maximum width of the associated opening. It is a preferred feature that the ends of the opening cut are angled in a manner corresponding to the angling, when folded back, of the laterally projecting portions towards the leading portion.
Preferably the flaps are dimensioned in such a way that during insertion of the leading portions do not clear the edges of the openings defined in the second end piece of the carton blank.
In certain embodiments the two pieces of paperboard are constituted by ends of a wraparound sleeve for containing one or more articles. Preferably two or more flaps are provided on one end of the sleeve and two or more corresponding openings are provided on the other end of the sleeve.
One preferred feature is that the ends of the openings are aligned on a fold line such that the free portion of the sleeve end hinges about the fold to in assist in the insertion of the flaps.
Another feature is that the fold comprises two end sections joined by a C-shaped cut extending away from the leading portion of the flap so that when folded back, a tab projects forwardly of the fold line.
Embodiments of the present invention will now be described in more detail in the accompanying drawings.